Art of refining



Dec. 5, 1933. E. c. HERTHEL 1,937,759

ART 0F REFINING Filed Dec. 24. 1952 2 Sheets-Sheet 1 INVENTOR Faye/7e Cflerf ie/ ATTORNEY 5 Dec. 5, 1933. Q HERTHEL 1,937,759

'ART OF REFINING INVENTOR Faye/76 C Her ffie/ ATTORNEYS Patented Dec. 51933 PATENT OFFICE ART or REFINING Eugene C. Herthel, Flossmoor, 111.,assignor to Sinclair Refining Company, New York, N. Y., a

corporation of Maine Application December 24, 1932 Serial No. 648,763

5 Claims.

This invention relates to improvements in the manufacture of gasoline bycracking higher boiling hydrocarbon oils, such as gas oil, attemperatures exceeding 900 F. to produce cracked gasoline of highanti-knock value.

The severe cracking temperatures utilized .to produce gasoline of highanti-knock value, temperatures exceeding 900 F. for example, tend toproduce gasoline fractions including lower boiling constituents, lowerboiling within the range of the gasoline fraction, in highconcentration, the production of such low boiling gasoline constituentsaccompanying, within limits, the production of even lower boilingconstituents incondensible at ordinary atmospheric temperatures andpressure. These severe cracking temperatures also tend to produceunstable hydrocarbon constituents which, although initially within theboiling range of gasoline, tend to polymerize to form higher boilingpolymers, gums for example. Such gasolines require stabilization bothphysically and chemically. This invention combines a physicalstabilization and a chemical stabilization in a particularlyadvantageous manner.

According to the present invention, the raw cracked gasoline fraction,produced by cracking at temperatures exceeding 900 F., is separated intotwo liquid fractions, one containing those constituents higher boilingthan butane and the other containing butane and lower boilingconstituents. The higher boiling separated fraction is contacted with anadsorptive catalyst, fullers earth or similar clays for example, at anelevated temperature, upwards of about, 350 F. and below the criticaltemperature of the separated fraction, under a pressure sufficient tomaintain the separated fraction substantially in liquid phase, and agasoline'fraction' free from constituents higher boiling than suitableas components of the gasoline product is distilled from this contactedfraction. Propane andlower boiling constituents are separated from thelower stantial proportion of higher boiling constitu ents. Polymersproduced by the oil-catalyst con- -tact will form at least a part ofthis necessary higher boiling fraction, but it is usually advantageousto have present a somewhat larger proportion of higher boilingcomponents. Such additional higher boiling components may be supplied aspart of the fraction subjected to contact with the adsorptive catalystor as an extraneous fraction added subsequent to the oil-catalystcontact. In the latter case, the added extrane ous fraction should befree from unstable constituents. Such an extraneous fraction may beadded prior to the oil-catalyst contact, and this part of the combinedoperation of the invention can thus be carried out in the mannerdescribed in Letters Patent Number 1,823,175, granted to SinclairRefining Company September 15, 1931, on an application of James G.Stafiord. This contact with an-adsorptive cata- 7. lyst may besupplemented, and particularly where carried out at temperatures belowabout 385 F. is with advantage supplemented, by a mild sulphuric acidtreatment. A relatively mild sulphuric acid treatment is usuallysufilcient in 39 this connection. By carrying out the oil-catalystcontact at higher temperatures, however, upwards of about 385 F., suchsulphuric acid treatment can usually be omitted. When the higher boilinginitially separated liquid fraction is contacted with the adsorptivecatalyst at temperatures in the higher range, the heat imparted to theoil in this connection is with advantage utilized in effectingdistillation of the gasoline frac' tion from the contacted fraction, byreducing the pressure on the contacted fraction while at maintainedelevated temperature.

Several important advantages are secured by the practice of thisinvention. The combined op eration includes a particularly advantageouschemical stabilization of the higher boiling components of the finalgasoline product. The emciency of thischemical stabilization, thecontact refining operation, is improved, and the capacity of anyparticular apparatus in which it is carried out is increased, byreducing the proportion of the final gasoline product subjected to theoilcatalyst contact. This reduction in the proportion of the finalgasoline product subjected to the contact refining is, moreover,accomplished,

in the combined operation of the invention, as a part of the physicalstabilization but without complication of that part of the operation.The elimination of the lower boiling gasoline components from thetraction contacted with the adsorptive catalyst not only reduces theburden on the contact-refining" part of the operation but also enablesthe separate chemical stabilization of this lower boiling part of thefinal gasoline product in a particularly advantageous manner, namely bytreatment with caustic alkali. An improved realization of the advantagesof the physical stabilization and the chemical stabilization, inseparate treatments of two distinct fractions, is further accomplishedby the particular manner in which they are combined in the process ofthe present invention. 7

The invention will be further described in connection with theaccompanying drawings. In the accompanying drawings, Fig. 1 represents,diagrammatically and conventionally, one form of apparatus adapted forcarrying out the invention, more particularly with temperatures in thelower range of oil-catalyst contact temperatures, and Fig. 2 represents,diagrammatically and conventionally, another form of apparatus adaptedfor carrying out the invention, more particularly with temperatures inthe higher range of oil-catalyst contact temperatures.

This invention is useful in conjunction with cracking processesgenerally in whichcracking is effected at temperatures exceeding 500 F.

Since the particular type of such cracking operations is not essentialto characterization of this invention, and since such crackingoperations are in themselves Well known, the drawings include noillustration of cracking-apparatus. The raw cracked gasoline or rawcracked gasolinecontaining fraction is delivered from the crackingapparatus to the tank 3 or the tank 103, in Figs. 1 and 2 respectively,in the apparatus illustrated in the drawings.

Referring more particularly to Fig. l, the raw cracked gasoline fractionis pumped from the tank 3, by means of pump 4, through a heat exchanger5 into a fractionating tower 6 in which it is separated into twofractions, one containing those constituents higher boiling than butaneand the other containing butane and lower boiling constituents.Fractionating towers so employed are commonly designated debutanizers.The operation of the fractionating tower 6 is controlled by theregulated circulation of a heating medium through the re-boiler 7 andthe regulated circulation of a cooling medium through the refluxcondenser 8. The heat required in this fractionating operation issupplied either through the reboiler 7 or in part through the re-boiler'7 and in part through the heat exchanger 5. The higher boiling fractionis discharged as a liquid from the re-boiler 7 through connection 9. Thevapor mixture escaping from the reflux condenser 8 is subjected tocondensation in the condenser 10, the condensate and uncondensed vaporsand gases are separated in the receiver 11, the uncondensed vapors andgases are discharged through connection 12 and the condensate isdischarged as a liquid through connection 13 to tank 14. Thefractionating tower 6 is, for example, operated under a pressureapproximating 100-150 pounds per square inch. Under these conditions theliquid fraction discharged from the re-boiler 7 through connection 9 isusually discharged at a temperature upwards of about 350 F. The higherboiling liquid fraction discharged through connection 9 is supplied tothe contact vessel 15 at the elevated temperature at which it isdischarged from the reboiler 'l. 350-385 F., for example, and under amaintained pressure, upwards of 100 pounds per square inch for example.In the contact vessel 15 this higher boiling fraction is contacted withan adsorptive catalyst, fullers earth or similar clays, at this elevatedtemperature and under a pressure sufficient to maintain this fractionsubstantially in liquid phase. The contacted fraction is discharged fromthe contact vessel 15 through cooler 16 into the tank 17, the pressureon the contacted fraction being reduced approximately to atmosphericpressure as it passes from the cooler 16 into the tank 17. i Thecontacted fraction is pumped from the tank 17 by means 01' pump 18through the treating vessels 19 in which it is subjected to treatmentwith sulphuric acid in a manner conventional except for the use ofrelatively small proportions of sulphuric acid, one pound of 66 B.sulphuric acid per barrel as compared to live to eight pounds of suchacid per barrel for example, and thence into tank 20. The contacted andacid-treated fraction is pumped from the tank 20 by means of pump 21through the heater 22 into the fractionating tower 23 in which agasoline fraction free from constituents higher boiling than suitable ascomponents of the gasoline product is separated from higher boilingcomponents of the contacted and acid-treated fraction and any extraneousfraction added to assist in the fractionation. Such an extraneousfraction, supplied through connection 24, may be admixed with thefraction entering the treating vessels 19 from the tank 17 or may beintroduced into the tank 20in amount suflicient to provide a higherboiling fraction to be separated in rrac= tionating tower 23 as acondensate approximating, for example, 10% of the lower boiling fractionseparated as a vapor mixture. The fractionating tower 23 is controlledby regulated circulation 01 a cooling medium through the refluxcondenser 25. The fractionating tower 23 is, for example, operated underapproximately atmospheric pressure, although by provision of appropriateconventional apparatus it may be operated under subatmospheric pressure.Considered alone, the operation of the heater 22 and the fractionatingtower 23 corresponds to the conventional re-rimning or redistillation oftreated gasoline, and is carried out in the conventional manner exceptin that in the combined operation of this invention the lower boilingpart of the gasoline is not included in the re-run" stock. The higherboil- I ing fraction separated in the fractionating tower 23 isdischarged through cooler 26. This fraction, for example, maybe suppliedto a cracking operation, the cracking operation producing the rawcracked gasoline fraction delivered to tank 3. The vapor mixtureescaping from the reflux condenser 25 is subjected to condensation inthe condenser 27, and the condensate is discharged as a liquid throughconnection 28 to tank 29. The lower boiling fraction separated in thefractionating tower 6 is pumped from the tank 14 by means of pump 30through a heat exchanger 31 into a fractionating tower 32 in whichpropane and lower boiling constituents are separated as a gas mixturefrom the remaining higher boiling constituents of the fraction.Fractionating towers so cmployed are commonly designated stabilizers..

The operation of the fractionating tower 32 is controlledby theregulated circulation of a heater 31. The separated gas mixture isdischarged through connection 34. The separated liquid fraction isdischarged through cooler and through the treating vessel 36 in which itis subjected to treatmentv with an aqueous solution of caustic alkali'inthe conventional manner to tank 37. The fractionating tower 32 is, forexample, operated under a pressure approximating 150-300 pounds persquare inch. The fractions accumulating in the tanks 29 and 37, jointlystabilized physically and separately stabilized chemically, are combinedand, by means of pump 38, are forced as 'a mixture constituting a fullboiling range gasoline productthrough the treating vessels 39 in whichthe mixture is subjected to-the The final is discharged throughconnecconventional sweetening operation. gasoline product tion 40. i

Referring more particularly to Fig. 2, the raw cracked gasoline fractionis pumped from the tank 103', by means of pump 104, through a heatexchanger 105 into a fractionating tower 106 in which it is separatedinto two fractions, one con-' taining those constituents higher boilingthan butane and the other containing butane and lower boilingconstituents Some pentanes may be separated with'the butane and lowerboiling constituents to ,insure complete separation of butane. Theoperation of the fractionating tower 106 is controlled by the regulatedcirculation of a heating medium through the re-boiler 107 and theregulated circulation of a cooling medium through the'reflux condenser108. The heat required in this fractionating operation is suppliedeither through the re-boiler 107 or in part through the re-boilei; 107,and in part through the heat exchanger 105. The higher boiling fractionis discharged as a liquid from the re-boiler 107 through connection 109.The vapor mixture escaping from the reflux condenser 108 is subjected tocondensation in the condenser 110, the condensateand uncondensed vaporsand gases are separated in the receiver 111, the uncondensed vapors andgases are discharged through connection 112 and the condensate isdischarged as a liquid through connection 113 to tank 114. .Thefractionating tower 106 is, for example, operated under a pressureapproximating 100-150 pounds per square inch. Under these conditions aliquid fraction discharged from'the reboiler 107 through connection 109is usually discharged at a temperature upwards of about 350 F. Thehigher boiling liquid fraction discharged through connection 109 ispumped, by means of pump 141, through the heater 122 and through thecontact vessel 115 into the fractionating tower 123. In the heater 122this fraction is heated, for example, to a temperature of 385-450 F.under a pressure sufficient to maintain this fraction substantially inliquid phase, a pressure approximating 250 pounds per square inch forexample. In the contact vessel 115 this fraction is contacted, under amaintained pressure, with an adsorptive catalyst, fulle'r's earth orsimilar clays, at the elevated temperature at which it is dischargedfrom the heater 122. The contacted fraction is discharged into thefractionating tower 123 through a valve line product is separated fromhigher boiling fraction to be separated in fractionating tower 123 asacondensate approximating, for example, 10% of the lower boiling fractionseparated as a vapor mixture. The fractionating tower 123 is controlledby regulated circulation of a cooling medium through the refluxcondenser 125. The fractionating tower 123 is, for example, operatedunder approximately atmospheric pressure, although by provision ofappropriate conventional apparatus it may be operated undersubatmospheric pressure. The higher boiling fraction separated in thefractionating tower 123 is discharged through cooler 126. This fraction,for example, may be supplied to a cracking operation, the crackingoperation producing the raw cracked gasoline fraction delivered to tank103. The vapor mixture escaping from the reflux condenser 125 issubjected to condensation in the condenser 127, and the condensate isdischarged as a liquid through connection 128 to tank 129. The lowerboiling fraction separated in the fractionating tower 106 is pumped fromthe tank'114 by means of pump 130 through a heat exchanger 131 into afractionating tower 132 in which propane and lower boiling constituentsare separated as a gas mixture from the remaining higher boilingconstituents of the fraction. The operation of the fractionating tower132 is controlled by the regulated circulation of a heatingmediumthrough there-boiler 114 and the regulated circulation of acooling medium through the reflux condenser 133. The heat required inthis fractionating operation is supplied either through the re-boiler144 or in part through the re-boiler 144 and in part through the heatexchanger 131. The separated gas mixture is discharged throughconnection 134. The separated liquid fraction is discharged throughcooler 135 and through the treating vessel 136 in which it is subjectedto treatment with an aqueous solution of caustic alkali in theconventional manner to tank 137. The fractionating tower 132 is, forexample, operated under a pressure approximating -300 pounds per squareinch. The fractions accumulating in the tanks 129 and 137, jointlystabilized physically and separately stabilized chemically, are combinedand, by means of pump 138, are forced as a mixture constituting a fullboiling range gasoline product through the treating vessels 139 in whichthe mixture is subjected to the conventional sweetening operation. Thefinal gasoline product is discharged through connection 140. v p

The uncondensed vapors and gases'discharged through connection 12, orconnection 112, usually contain gasoline constituents which make itappropriate to subject this vapor mixture to conventional recoveryoperations. The gas mixture escaping through connection 34, orconnection 134, is usually substantially free from condensable gasolineconstituents.

I claim:

1. In the manufacture of gasoline by cracking higher boiling oils attemperatures exceeding 900 F., the improvement which comprisesseparating the raw cracked gasoline fraction into two liquid fractions,one containing those constituents higher boiling than butane and theother contain- 150 ing butane and lower boiling constituents, contactingthe higher boiling separated fraction with an adsorptive catalyst at anelevated temperature upwards of about 350 F. and below its criticaltemperature under a pressure sufficient to maintain it substantially inliquid phase, distilling a gasoline fraction free from constituentshigher boiling than suitable as components of the gasoline product fromthe contacted fraction, separating propane and lower boilingconstituents from the lower boiling initially separated fraction,treating the higher boiling separated fraction from the last mentionedseparation with caustic alkali, and combining the alkali treatedfraction and the distilled gasoline fraction.

2. In the manufacture of gasoline by cracking higher boiling oils attemperatures exceeding 900 F., the improvement which comprisesseparating the raw cracked gasoline fraction into two liquid fractions,one containing those constituents higher boiling than butane and theother containing butane and lower boiling constituents, contacting thehigher boiling separated fraction with an adsorptive catalyst at anelevated temperature upwards of about 350 F. and below its criticaltemperature under a pressure suificient to maintain it substantially inliquid phase, treating the contacted fraction with sulphuric acid,distilling a gasoline fraction free from constituents higher boilingthan suitable as components of the gasoline product from the contactedand acid treated fraction, separating propane and lower boilingconstituents from the lower boiling initially separated fraction,treating the higher boiling separated fraction from the last mentionedseparation with caustic alkali, and combining the alkali treatedfraction and the distilled gasoline fraction.

3. In the manufacture of gasoline by cracking higher boiling oils attemperatures exceeding 900 F., the improvement which comprisesseparating the raw cracked gasoline fraction into two liquid fractions,one containing those constituents higher boiling than butane and theother containing butane and lower boiling constituents, contacting thehigher boiling separated fraction with an adsorptive catalyst at anelevated temperature upwards of about 350 F. and below its criticaltemperature under a pressure sufficient to maintain it substantially inliquid phase, distilling a gasoline fraction free from constituentshigher boiling than suitable as components of the gasoline product froma mixture including the contacted fraction and an added fractionincluding higher boiling constituents, separating propane and lowerboiling constituents from the lower boiling initially separatedfraction, treating the higher boiling separated fraction from the lastmentioned separation with caustic alkali, and combining the alkalitreated fraction and the distilled gasoline fraction.

4. In the manufacture of gasoline by cracking higher boiling oils attemperatures exceeding 900 F., the improvement which comprisesseparating the raw cracked gasoline fraction into two liquid fractions,one containing those constituents higher boiling than butane and theother containing butane and lower boiling constituents, contacting thehigher boiling separated fraction with an adsorptive catalyst at anelevated temperature upwards of about 385 F. and below its criticaltemperature under a pressure sufficient to maintain it substantially inliquid phase, distilling a gasoline fraction free from constituentshigher boiling than suitable as components of the gasoline product fromthe contacted fraction, separating propane and lower boilingconstituents from the lower boiling initially separated fraction,treating the higher boiling separated fraction from the last mentionedseparation with caustic alkali, and combining the alkali treatedfraction and the distilled gasoline fraction.

5. In the manufacture of gasoline by cracking higher boiling oils attemperatures exceeding 900 F., the improvement which comprisesseparating the raw cracked gasoline fraction into two liquid fractions,one containing those constituents higherboiling than butane and theother containing butane and lower boiling constituents, contacting thehigher boiling separated fraction with an adsorptive catalyst at anelevated temperature upwards of about 350 F. and below its criticaltemperature under a pressure sufficient to maintain it substantially inliquid phase, distilling a gasoline fraction free from constituentshigher boiling than suitable as components of the gasoline product fromthe contacted fraction by reducing the pressure thereon while atmaintained elevated temperature, separating propane and lower boilingconstituents from the lower boiling initially separated fraction,treating the higher boiling separated fraction from the last mentionedseparation with caustic alkali, and combining the alkali treatedfraction and the distilled gasoline fraction.

EUGENE C. HERTHEL.

@ERTIFHCATE 0F (IQRRECTION.

Patent No. l, 937, 759,

December 5, 1933.

EUGENE 6. HERTHEL.

it is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows:

Page 2, line 27, tor

"500" read 900; and that the said Letters Patent should be read withthis correction therein that-the samemay conform to the record of thecase in the Patent Office.

Signed and sealed this9th day of January, l). 1934.

(Seal) F. M. Hopkins Acting Commissioner of" Patents.

